The I.sup.2 C or IIC bus is a standard bus (see "I.sup.2 C Bus Specification" Philips, January 1983) for transmitting data, and is a synchronous serial bus consisting of a Clock (SCL) and Data (SDA) line.
The 3-wire bus is another standard bus which is commonly used (for example, see the data sheet for Motorola part no. MC145170, PLL frequency synthesizer). The bus is also a synchronous serial bus having a clock which, in addition to clock and data lines, has an ENABLE line to permit data transfer.
With increasing use of multi standard systems, e.g. televisions, video devices, which can operate with a variety of standards, it would be desirable to provide a relatively simple means, for incorporation into a receiver or peripheral device, which can accept and discriminate between I.sup.2 C and 3-wire bus formats.